Process for the production of aldol



06L 1932' M. MUELLER-CUNRADI ET AL 1,831,853

PROCESS FOR THE PRODUCTION OF ALDOL I Filed June 9, 1928 ACETALDCHYOE.CONDENSOZ ACETA LDEHYDE Fig.1.

TKICKLING'TOWEE CAUSTIC SODA SOL. I

ETALEHYDL CAUST'IC SODA SOL MIXING VESSEL TKICKLING TOWER.

MIXING CAUSTIC. VESSEL SODA con DEN Son.

III

MIXING VESSEL DENSOE.

CAUSTIC SODA 50L ALDOL MIXING VESS NZUTEALIZEE.

F" ACETALDEHYDE 1 Co I uuansza d2 3 :Aus-r:c. 1 h v I SODA 50L. I Z coND ENSO'R.

MINING VESSEL T -B 5' CAUSTIC SODA r 50L. 4 CONDENSQR- MIXING VESSEL 2,2F r l--) ALDOL- CAUSTIC v SODA 50L. 6

CAUSTIC 2-; MIXING VESSEL T A D 3 EL 2/ immune VESSEL '&f 3noentow mun;'77lucgfn-Cunmdz' XurZ z'crc @lleirflbtom Patented Oct. :11, 193 2UNITED STATES PATENT OFFICE 4 MARTIN MUELLER-GUNRADI AND KURT PIEROH, OFLUDWIGSHAFEN-ON-THE-RHINE, GERMANY, ASSIGNORS TO I.- G. FARBENINDUSTRIEAKTIENGESELLSCHAFT, OF FRANKFORT-ON-THE-MAIN, GERMANY, A CORPORATION OFGERMANY IBOGESS FOR THE PBODUQTION OF ALDOL Application filed June 9,1928, Serial No. 284,270, and in Germany June 27, v1927.

'15 are externally cooled. Or the tubes may be mounted in bundlesimmersed in a common cooling medium, or any other convenient or suitablearrangements enabling heat to be efl'ectually removed may be used. Ithas also been found advisable to allow the temperature of the reactionmixture to rise during its passage through the apparatus. This can beeffected, for example, by connecting a number of cooling devices inseries, each of them being a a higher temperature than the previous one.It may also be of advantage to add the condensing agent in successiveportions instead of all at one time.

In general, it is advisable that the condensation of the acetaldehyde toaldol should not be carried to completion, but that the process shouldbe interrupted as soon as a considerable amount of the acetaldehyde hasbeen converted. At the same time, a very pure aldol can be obtained ifmeasures be taken to secure the continuous removal of the undecomposedaldehyde and any water and other products which may be present, forexample by means of a blast of steam or other densing agent or renderingit inactive. A particularly advantageous method of working is first toexpel the water and a portion of the acetaldehyde by moderate heatingunder l5 diminished pressure, and then to'extract the remainder of theacetaldehyde from the aldol by a further rise in temperature, also underdiminished pressure. Care must be taken to keep the temperature belowthe decomposition temperature of the aldol. If necessary,

acetaldehyde need be in the apparatus at gases, if need be, afterremoving the congases or vapors may be passed through the reactionmixture, in order to obtain a. more rapid removal of the water,undecomposed acztaldehyde and any other substances prese11 r- By meansof the process according to this Invention the production of aldol canbe carrled on in a continuous manner with great technical advantage.Apart from the advantages resulting from continuous working, such ashigh output per unit of time and space, combined with low runningcosts,the process offers the considerable advantage over intermittent workingin the fact that only small quantities of the inflammable any giventime.

The process of the present invention may be performed in an apparatus,for example, as will be further explained in the following withreference to the annexed drawing in which Figure 1 shows an apparatusfor the continuous preparation of aldol when employing a system ofmultiple straight pipe condensers and Figure 2 when employingra seriesof coil condensers. In order to be as brief as possible the arrangementswill be explained while explaining the method of working therewith. Themixing vessel T is fed with acetaldehyde from the pipe l and withcaustic soda solutionfrom the pipe I and the mixture runs after mixingthrough the pipe line 2 to the first condenser A. The product then runsthrough the pipe line 3, the mixing vessel T and the pipe lined to thecondenser B and subsequently throughthe pipe line 5, the mixing vessel Tand'the pipe line 6 into the condenser C and from this through the pipeline 7, mixing vessel T, and pipe line 8 through the condenser D. Themixing vessels T T and T can be fed with caustic soda solution throughthe pipe lines II, III and IV depending on the requirements. Through thepipe line 9 the re-- action product leaves the condenser D andis'neutralized in the mixing vessel T, by the additionof acid throughpipe line V. After neutralization the reaction product is fed into thetop of tower E which is provided with fillers and the product is freed,by heat-- 100 ing, from the main quantity of acetaldehydewhich latterafter condensation in the con-.

denser F, connected with the tower by the pipeline 11, is returned tothe first condenser A b means of the pipe line 12. The aldol whic leavesthe tower E at the bottom and which is considerably freed from aldehydeis passed into a second tower G by means of. the pipe line 13 in whichtower the last traces of aldehyde are removed and drawn ofi through thepipe 14. If required,

K the tower G can be kept at a higher temperature than the tower Eandthe removal of the aldehyde from both the towers can be performed at apressure below atmospheric pressure. The quantities of aldehyderecovered can be fed into the mixing vessel T and the aldol which isfreed from acetaldehyde is drawn ofi throughvthe pipe 15.

Working with the apparatus shown in Figure '2 is the same as explainedabove with reference to Figure 1. v

. The following example will further illustrate the nature of t isinvention, which however is not restricted thereto.

Example Four spiral tubes, arranged in series are witlu fillers or thelike in which a reduced 7 action mixture being i pressure is maintained.The bulk of the water and some of the acetaldehyde escape, and theproduct is then run througH a second tower at about C. in which theremainder of the acetaldeh (ie is extracted in vacuo and canbe returnedirectl to the reaction. The reaction. product is a dol of suflicientpurity to be used for many purposes, such fllir eizample ashydrogenation to butylene co g llVhat we claim is:

1. A. process for the prodnction of aldol.

from acetaldehyde which comprises continuously passing a mixturecomprising aoetaldehyde and a condensing agent through a cooled reactionchamber.

2. A process for the production of aldol from acetaldehyde whichcomprises continuously passing a mixture comprising acetaldea cooledreaction chamber, the condensing agent employed being added at differentp aces of the reaction chamber during the passage of the reactionmixture therethrough. 4. process for the production of aldol fromacetaldehyde which comprises continuousl passing a mixture ,compr' ingacetalde yde and a condensing agent thlfb ugh a cooled reaction chamber,the condensing agent employed being added at different places of thereaction chamber during the passa of the reaction mixture therethroughand t e temperature of the reaction mixture being gradually raisedduring the pmage throug the reaction chamber by gradually reducmg theintensity of the cooling.

5. A process for the production of aldol from acetaldehyde'whichcomprises continuously passing a mixture comprising acetaldehyde and acondensing agent through a cooled reaction chamber, continuouslyseparating crude aldol from the aqueous reaction mixture containingacetaldehyde and continuousl removing water and remainders of acetaldeyde from theseparated crude aldol.

6. A process for the production of aldol from acetaldehyde whichcomprises con-. tinuousl passing a mixture comprising acetalde yde and acondensing agent through a cooled reaction chamber, continuouslyrendering neutral the reaction mixture contaming aldol, acetaldehyde andwater, continuously separating crude aldol from the resulting aqueousmixtureand continuously removing water and remainders of acetaldehydefrom the separated crude aldol- In testimony whereof we have hereuntoset our hands.

MARTIN MUELLER-GUNRADI. KURT PIEROH. I

hyde and a cbndensing agent through a cooled reaction chamber, thetemperature of the readually raised during 7 the passage through t ereaction chamber.

3. A proces for the production of aldol from acetaldehyde whichcomprises continuously assing a mixture co mprising acetalde e and acondensing agent t rough

